If the exoplanet HD 100-546 is larger than some stars, how come it hasn’t collapsed into a low-mass star?
In: Physics
On Earth, if an object gains more material, it gets bigger.
But with GAS planets and stars, if the planet gets more gas material, gravity gets stronger, so it pulls the gas more, so the planet or star gets slightly smaller.
Basically, mass shrinks the planet, and creates more pressures and heat in the core, until the pressure and temperature are sufficient for nuclear reactions. At which point the heat from the nuclear may create extra pressures and inflate the star again.
Anyway, big (volume) does not necessarily mean heavy (mass), so you CAN have a visually big planet that is lightweight, by gas giant standards, and not have enough mass to have nuclear reactions and be a star.
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